It is well known that the human ear is subject to serious damage by exposure to excessive sound or concussive pressures. It is also well known that the entry of water into normally healthy ears often precipitates the onset of ear infections which may result in potentially serious complications. Persons who suffer from chronic middle-ear disease with perforation of the tympanic membrane, Otitis Externa or Media, Otomycosis or Otorreah must constantly guard against the introduction of water to the auditory canal or face serious consequences. These persons cannot safely shower, shampoo, bathe, swim or even be caught in the rain without risking the dangerous possibility that water may enter the ear. To prevent irreversible damage, persons subject to these conditions must utilize means to effectively exclude sound and/or water from the auditory canal.
Many devices and appliances have been developed to provide protection to individuals who must endure high noise levels or who suffer from disorders of the auditory system. As early as 1912 efforts were being made to attenuate sound and lessen the effects of concussive pressures to prevent damage to the ear.
In U.S. Pat. No. 1,016,877 Elliott disclosed an earplug which is strikingly similar to many in current usage. Von Gierke in U.S. Pat. No. 2,719,523 discloses a sound attenuating earplug which provides either positive or negative pressure within the auditory canal to cause a flexure of the tympanic membrane to reduce it's sensitivity to certain frequencies of the sound spectrum.
Expansive earplugs, in many forms, are disclosed in the prior art; by Wasserman in U.S. Pat. No. 2,876,767 wherein a balloon-like earplug is inflated by an externally attachable bulb or syringe; by Mendelson in U.S. Pat. No. 3,110,355 wherein a liquid is injected into a peripheral expansive chamber about a sound transmitting tube to cause said chamber to expand into positive contact with the auditory meatus; by Harvey in U.S. Pat. No. 3,505,999 who utilizes an expandable bag which is pressurized by a syringe-like pump and by Victoreen in U.S. Pat. No. 3,602,654 wherein hydraulic pressure is again utilized to expand a fluid-expandable means into close fitting engagement with the wall of the auditory canal.
In U.S. Pat. No. 3,783,864 Moller discloses an earplug which is expanded by the application of mechanical compression along the longitudinal axis of the insert to cause sealing engagement with the auditory meatus. In U.S. Pat. No. 3,800,791 Visor teaches a method whereby a flexible earplug is expanded by forcing a piston-like expander into the core of the earplug thereby creating an earplug which fits all sizes of auditory canals and Coehorst in U.S. Pat. No. 4,006,796 discloses an earpiece which substantially consists of a thin-walled flexible capsule filled with a jelly-like compound and means to compress said compound into said capsule to cause it to expand into engagement with the inner wall of the ear.
Plastic memory is utilized by Gardner, Jr. in U.S. Pat. No. 3,811,437, by Lewis in U.S. Pat. No. 3,881,570, by Kalayjian in U.S. Pat. No. 4,724,922 to cause earplugs to expand after compression and insertion into the ear canal.
A pneumatic shaping earplug is disclosed by Rose in U.S. Pat. No. 4,089,332 wherein a diaphragmatic member, upon depression, causes a reduction in the volume of the earplug which reacts to said reduction by expanding peripherally in response to the increased pneumatic pressure within said reduced volume.
Earplugs which are connected by flexible means for prevention of loss or for acoustic purposes are disclosed in U.S. Pat. Nos. by; Hill in 3,415,246; Wacker in 4,193,369; Powers et al in 4,253,425; and Westerdahl in 4,314,553.
In U.S. Pat. No. 4,134,153 Voorhees discloses an ear protector which is worn externally of the auditory canal, having pressure-sensitive adhesive means for securing said ear protector to the skin surrounding the base of the ear, further emphasizing the requirement for preventing the entrance of foreign matter or fluid into the auditory canal.
Other recent developments in ear protection technology are disclosed in U.S. Pat. Nos. by; Asker in 4,384,575; Parker et al. in 4,406,282; and Leight in 4,774,938. While these disclosures have no relevance to the present invention, they are herein cited to illustrate the long-standing and continuing effort to provide maximum protection to the delicate elements of the auditory system.
While all the examples of the prior art provide some measure of benefit or protection for the user, concern exists that the use of pneumatically or hydraulically expanded earplugs may possibly represent a hazard potential to the user greater than the benefits or protection to be derived from their use.
Laboratory testing confirms that pneumatic pressures in excess of 300 mm.Hg. are easily developed through the use of a bulb-type syringe. Pressure of this magnitude could possibly cause the rupture of the thin membrane of the earplug, resulting in catastrophic damage to the delicate auditory system. Further, as the pneumatically expanded earplugs come into engagement with the inner circumference of the auditory canal, peripheral expansion ceases and longitudinal expansion begins, making it possible for said earplug to elongate into contact with the tympanic membrane thereby causing possible permanent damage to this delicate tissue.
Pressures achievable through the use of a piston-type syringe acting upon a hydraulic media are of an even greater magnitude and due to the incompressible nature of said hydraulic media, the reaction to movement of the piston is instantaneous, creating an even greater potential for tragic result. This hazard is further compounded when these devices are employed by persons who are untrained in their use.
One other problem associated with the use of pressure-expandable earplugs which employ an externally attachable or detachable pressurizing means is the requirement that the user is subject to the inconvenience of having to carry said pressurizing means in order to be able to utilize said earplugs.
Tests, conducted on a plurality of individuals, have shown the average pressure achievable by the human pulmonary system, when mouth-blown into a flexible plastic tube of an outside diameter of 7.65 mm., to be 93.33 mm.Hg., while the maximum pressure achieved by any individual was 128 mm.Hg. While the pulmonary system may posess the capability of producing greater pressure, the musculature of the lips was incapable of preventing leakage around said small diameter tube.
It is concluded that mouth-blown pressures are self-limiting and as a consequence would be incapable of causing the rupture or over-elongation of well designed inflatable earplugs.
It is the object of the present invention to provide pneumatically inflatable earplugs comprising means whereby the user causes the expansion of said earplugs through the application of self-developed pulmonary pressure. It is a further object of this invention to provide inflatable earplugs which may be safely expanded by an untrained user, to bring said earplugs into positive sealing engagement with the auditory meatus to prevent the entry of damaging sound pressures, concussive shock-waves, foreign matter or fluids into the auditory canal. It is yet a further object of the present invention to provide expandable earplugs for use by infants, the infirm or the handicapped, which may be safely inflated by a care-giver, to provide the aforesaid benefits and protection to these individuals.